A device of this type is already known from French Pat. No. 2,419,883 (U.S. Pat. No. 4,242,852) to the same assignee. With respect to the device described in U.S. Pat. No. 3,925,961 to the same assignee the device described in French Pat. No. 2,419,883 sought to:
1. Increase the productivity of the equipment by reducing the waiting time between two consecutive sterilizing cycles in the autoclave; PA1 2. Provide a less complex and less fragile system from the mechanical point of view, taking into account the harsh conditions which prevail in an autoclave; PA1 3. Allow horizontal loading of the bags so as to prevent them from collapsing and being deformed in the autoclave under the effect of the heat and their own weight.
In French Pat. No. 2,419,883, the actuating means associated with the movable bars of the compression and sealing means are formed by inflatable seals. Inflatable seals have several advantages. They allow a uniform pressure to be obtained over the whole length of the bars of the compression and sealing means, which is one of the essential conditions for obtaining correct sealing of the bags and for insuring that the products contained therein will remain sterile until the time when they are used. Furthermore, inflatable seals require little space in height, so that they may be disposed between two pairs of compression and sealing bars. The result is that, for a rack of a given height, it is possible to process simultaneously a large number of bags disposed horizontally and stacked on top of each other, thus contributing to increase the productivity of the packing and sterilizing device.
However, inflatable seals capable of withstanding the harsh conditions which prevail in an autoclave, do not allow both a long stroke of the movable bars of the compression sealing means and a high sealing pressure to be obtained at the same time, this latter being also an essential condition for obtaining correct sealing. By way of indication, the inflatable seals used in the device described in French Pat. No. 2,419,883 only allowed a short stroke of said movable bars of about 2 mm so that the slit formed between each pair of bars only has small width. In use, this has proved to have several drawbacks. In fact, before sterilizing, the plastic bags are relatively soft, so that it is difficult to introduce their open ends into the slits of such a small width. In addition, the small width of the slits hinders the penetration of vapor into the bags and evacuation thereof. This leads to a lower sterilizing safety and involves consequently a longer sterilizing time so as to be sure that correct sterilization has been obtained. It follows that the total time for the packing and sterilizing cycle is longer, which adversely affects the productivity of the packing and sterilizing device.